A touch panel is well-known in the art as a typical switch of a thin type. In brief, the touch panel is a panel-type switch which has at least one switch part and can operate it with a substantially zero push-in stroke, or a panel-type switch having at least one switch part which can be operated by touching or lightly pushing the same.
In relation to touch panels, there are 1) a resistor film type (this is also called a transparent electrode type. Identical for the rest) opposing upper and lower transparent electrodes to each other between a transparent thin plate with a small space, 2) a photoelectric type cutting off or damping light outgoing from a light emitting device and entering a photodetector with a finger or the like, 3) an ultrasonic wave type of cutting off or damping ultrasonic waves outgoing from an ultrasonic oscillation device and entering a receiving device, and the like.
A touch panel 4 shown in FIG. 1 is of the resistor film type, and in brief, it is formed by providing at least one switch part which is turned on by being pushed from the exterior lightly (namely, with a substantially zero stroke) between transparent thin plates. In detailed description, this touch panel 4 is formed by superposing a transparent thin plate 10 having a plurality of opening portions 12 on a transparent thin plate 6 which is formed with a transparent electrode 8 on its upper surface, and superposing a transparent thin plate 16 which is formed with a transparent electrode 18 on its lower surface further thereon. The transparent electrodes 8 and 18 may be a plurality of stripy electrodes which are perpendicular to each other, or one electrode, e.g., the transparent electrode 18 may be a plurality of electrodes and the other electrode, e.g., the transparent electrode 8 may be a common electrode. The transparent thin plates 6 and 16 have flexibility since the same are thin plates. However, the lower transparent thin film 6 may not have flexibility.
Switch parts 4a are formed in portions of the respective opening portions 12, and when the portion of a desired opening portion 12 is lightly pushed from the transparent thin plate 16 side in this example, the transparent thin plate 16 and the transparent electrode 18 in the pushed portion are deflected so that the transparent electrode 18 comes into contact with the lower transparent electrode 8 through the opening portion 12 to be electrically turned on. However, the size, shape, number etc. of the respective switch parts 4a are arbitrary, and a plurality of small switch parts 4a may be electrically connected in parallel with each other to be employed as a single integrated switch part.
It is possible to form a display panel with switches by superposing such a touch panel 4 on a display panel 2 having an information display function as shown in FIG. 2, for example. Such a display panel with switches is disclosed in JP-U-61,723 (1986), for example. The display panel 2 is typically a liquid crystal display.
On the display panel 2, display regions 2a displaying contents selected by operation of the switch parts 4a such as control contents in an FA apparatus, destinations in a ticket-vending machine or the like, for example, are formed around lower portions of the switch parts 4a of the touch panel 4 in general, as shown in FIG. 3, for example. Thus, selection-operation of a desired switch part 4a is made easy.
The aforementioned touch panel 4 has such an advantage that the same is extremely thin with a thickness of about 1 mm at the most as a whole, while there is such a problem that the push-in stroke for the switch part 4a is extremely small at about zero (in more concrete terms, about 0.1 to 0.2 mm) and hence displacement thereof cannot be recognized by a human finger and hence "stroke feeling" of operating the switch parts 4a cannot be attained. The stroke feeling is also called "operation feeling".
When the stroke feeling cannot be attained, the person who has operated any switch part 4a may feel so uneasy that he repeatedly and excessively strongly presses/operates the switch part 4a although the switch part 4a has already been turned on since he has felt no operation of the switch part 4a. Particularly when he pushes it with a globe, he can attain absolutely no stroke feeling.
The aforementioned photoelectric and ultrasonic wave type touch panels are also operated by touching surfaces thereof etc. with a finger (i.e., with a zero push-in stroke), and hence stroke feeling cannot be attained.
A display panel with switches shown in FIG. 4 is proposed as that solving the problem of such a stroke feeling shortage of the touch panel. Such a technique is disclosed in JP-A-644,857 (1994), for example.
This display panel with switches has a structure obtained by providing a switching unit 20 on each display region 2a of the aforementioned display panel 2 respectively.
Each switching unit 20 comprises a housing 22, a transparent push button 24, a switching mechanism 26 which is operated by this push button 24, and an image guide 28. The switching mechanism 26 has an electrical contact and a return spring for returning this electrical contact and the push button 24 (both are not shown). The image guide 28 is formed by bundling and integrating a plurality of optical fibers, whereby the display content of the display panel 2 can be floated up to an upper surface of this image guide 28. Such an image guide 28 is provided, for the purpose of preventing such a situation that the distance between the surface of the display panel 2 and the push button 24 inevitable increases due to the provision of the switching mechanism 26 and the display content of the display panel 2 is displayed in a considerably deep portion of the push button 24 to become inconspicuous in this state.
While stroke feeling can be attained in this display panel with switches since a push-in stroke for the push button 24 can be ensured to some extent, the thickness of the switching unit 20 is large since the mechanical switching mechanism 26 is employed, and hence the image guide 28 is necessary for the aforementioned reasons and there are the following problems following this: Namely, the image guide 28 is formed by bundling a plurality of optical fibers as described above, and the picture quality is coarse and fine-grained display is difficult since there is a limit in increase of the number of the optical fibers. Further, light is emitted from upper end surfaces of the optical fibers forming the image guide 28 only in a range of about 70 degrees from just above at the most, and hence the display content of the display panel 2 is hard to recognize from an oblique direction. Further, such an image guide 28 is so high-priced that the overall display panel with switches is also high-priced.
A situation in case of employing such a conventional display panel (control panel) with switches for a control panel is now described.
In a control panel which is employed in a factory or the like, information necessary for a human for performing operation, driving, recognition, monitoring, maintenance and the like on a system which is constructed by machines equipment and the like is integrated, and the control panel is importantly placed as a man-machine interface mediating between the human and the machines.
Therefore, it is desired that the control panel is a man-machine interface which is friendly to the human and considerate toward a human engineering aspect capable of providing handiness, in order to reliably, efficiently and safely work the system.
While a skilled operator performs operation/driving of a system in a factory etc. in a control panel in a system such as an FA apparatus, a general human operates an apparatus as an operator in a system such as a ticket-vending machine in the yard of a railway station, for example, and it is extremely important to attain improvement of handiness and operability. The ticket-vending machine or the like is also referred to as a control panel in the broad sense here.
There are two necessary and indispensable man-machine interface functions for the control panel in the aforementioned system as viewed from the human who is an operator, and one is that the human recognizes the state of the machine and the other is that the human operates the machine.
Namely, it is a basic operation that the state in the system is displayed on the control panel by a display, the human recognizes and decides the displayed information, and the human operates the operation apparatus of the machine.
Therefore, to improve handiness as a control panel can be expressed in other words that improvement of operability for the human and improvement of recognition for the human, i.e., improvement of displayability is important.
Information displayed on the control panel includes fixed information in which the display content is fixed and variable information which can freely change the display content, and conventional examples of devices utilizing these information display means are described with reference to FIG. 5 and FIG. 6 respectively.
FIG. 5 shows an example comprising variable information display means, indicating a panel surface of a control panel CPI which is generally used at present.
On the panel surface, a liquid crystal display as a display panel 2 for displaying information such as a control content in an FA apparatus or the like is provided.
The liquid crystal display is an example of a display panel which can freely change the display screen by setting of a program of software, i.e.. which can perform display of variable information.
And, a touch panel 4 is set on the display panel 2, in such a structure that a plurality of switch parts 4a comprised in this touch panel 4 are opposed to and superposed on display regions of the display panel 2 respectively.
Such a touch panel 4 used in a conventional touch panel type display device TPD has such a property that stroke feeling cannot be attained as already described. Thus, the operator may feel so uneasy that he repeatedly presses/operates the switch part 4a although the switch part 4a has already been turned on since he has felt no operation of the switch part 4a.
In order to remove such uneasy feeling of the operator, a liquid crystal display displaying variable information is employed as a display panel DP while an operation switch assembly consisting of illuminant push button switches ISW comprising name plates or membrane switches MSW printed/noted on surface parts is separately provided around the liquid crystal display for attaining stroke feeling in pressing/operation as a panel surface of a control panel CP2 shown in FIG. 6. for example. These name plates and printing/noting function as fixed information display means.
In such a device employing a liquid crystal display and an operation switch assembly together, however, the panel surface increases in size since an operation switch group is separately provided in the marginal part of the liquid crystal display although stroke feeling can be attained, while it is necessary to make the number of the operation switches increase in response to the information number in order to display numerous information since the operation switch assembly is limited to display of fixed information, and the device increases in size.
Further, it is necessary to compare and operate the display screen and the operation switches since the operation switch assembly is separately set in the marginal part of the liquid crystal display, and a malfunction easily takes place and operability is extremely inferior.
In addition, it is necessary to remake a panel surface which is responsive to the number of the assembled operation switches when change of the specification of the control panel or the like takes place, leading to increase in cost along, with increase of the operation step number.
As in the above description, numerous display is enabled in an operation display device of a small panel surface in the touch panel type display device shown in the example of FIG. 5 since the same can attain diversification of display information and operation information by program setting of software, while the so-called operability is inferior since the human cannot have an operating sense, and we cannot help saying that consideration is insufficient also in view of human engineering.
On the other hand, a switching device assembly is arranged for fixed information in addition to the variable information display device in the example of the control panel shown in FIG. 6, and hence operability for the human is by far improved by employing these switches, and the human can attain an operating sense. However, it comes to that an extremely large number of switches are arranged in the periphery of the variable information display device, and the control panel increases in size since a large area is necessary, and compaction is made difficult.
As described above, a case of only variable information or only fixed information is rare as information displayed on the control panel, and cases where variable information and fixed information coexist are rather general such that various types of apparatuses are arranged as in the control panel surface shown in the example in FIG. 6 in most cases.
In case of looking at the overall panel surface, therefore, there is a restriction on layout with respect to arrangement of apparatuses for display of variable information and apparatuses for a display operation of fixed information and the like as shown in FIG. 6, while neat feeling is hard to attain and it comes to a complicated impression since designs etc. are absolutely different, and it cannot be said sufficient in human sensitivity engineering.